Procedure - HP 70427A User Manual

Procedure

Phase Noise Measurement <26.5 GHz User Control
Step 1 - Preset the downconverter
First, make sure the downconverter's ACT indicator light is lit. If it isn't do
the following:
1. Press the key.
DISPLAY
2. Press the
NEXT INSTR
indicator lights up.
3. Press the
INSTR PRESET
Step 2 - Determine the downconverter's IF frequency.
The downconverter's IF frequency will be displayed on the
downconverter calculates this frequency when an input frequency is entered.
First enter the DUT frequency into the downconverter as follows:
1. Press the softkey.
Freqs
2. Press the
INPUT FREQ
3. Enter the frequency with the numeric keypad.
4. Press the , ,
GHz MHz
5. Read the IF frequency from the
Step 3 - Decide which instrument to tune
There are three choices for phase locking: by using either the DUT; the
reference source; or for frequencies
be turned.
Tuning the HP 8662A/3A
If the DUT is referenced to an oven stabilized oscillator, the HP 8662A/3A
can be tuned. Connect the tune line to the EFC input. The limitation is that
the HP 8662A/3A's EFC can only track a drift of 10
frequency from the downconverter.
The HP 8662A/3A can also be tuned by setting the modulation to DC FM.
Refer to the HP 3048A manual for more information on tuning the
HP 8662A/3A.
Tuning the HP 70427A
If the DUT is a room-temperature oscillator, the downconverter's LO should
be tuned. The downconverter's tuning sensitivity can be selected so that it's
tuning range will be greater than the expected drift of the DUT.
The choices are:
softkey, repeatedly if necessary, until the ACT
key.
softkey.
or softkey.
kHz, Hz
display.
IF:
≥
1.5.GHz the downconverter's LO can
HP 70427A/HP 70428A User's Guide 3-3
Downconverter Operation
display. The
IF:
-8
of the output